Process for making organic compounds and the organic compounds made therefrom

ABSTRACT

A compound of formula II is prepared by: reacting a compound of formula F with  1 -chloro- 3,5 -dibromobenzene to form a compound of formula G; 
     
       
         
         
             
             
         
       
         
         
           
             reacting the compound of formula C with pinacol diborane to form a compound of formula H; 
           
         
       
    
     
       
         
         
             
             
         
       
         
         
           
             reacting the compound of formula H with  1 -bromo- 3 -iodobenzene to form a compound of formula J; and 
           
         
       
    
     
       
         
         
             
             
         
       
         
         
           
             reacting the compound of formula J with pinacol diborane to form a compound of formula K; and 
           
         
       
    
     
       
         
         
             
             
         
       
         
         
           
             reacting the compound of formula K with  3,5 -dibromopyridine to form the compound of formula II.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.12/492,716, filed Jun. 26, 2009, now copending, the entire disclosure ofwhich is incorporated herein by reference.

BACKGROUND

The invention relates generally to processes for making organiccompounds useful, e.g., as electron-transporting materials and/or holeblocking materials of optoelectronic devices and intermediates thereof,and the organic compounds made therefrom.

Optoelectronic devices, e.g. Organic Light Emitting Devices (OLEDs),which make use of thin film materials that emit light when subjected toa voltage bias, are expected to become an increasingly popular form offlat panel display technology. This is because OLEDs have a wide varietyof potential applications, including cell phones, personal digitalassistants (PDAs), computer displays, informational displays invehicles, television monitors, as well as light sources for generalillumination. Due to their bright colors, wide viewing angle,compatibility with full motion video, broad temperature ranges, thin andconformable form factor, low power requirements and the potential forlow cost manufacturing processes, OLEDs are seen as a future replacementtechnology for cathode ray tubes (CRTs) and liquid crystal displays(LCDs). Due to their high luminous efficiencies, OLEDs are seen ashaving the potential to replace incandescent, and perhaps evenfluorescent, lamps for certain types of applications.

OLEDs possess a sandwiched structure, which consists of one or moreorganic layers between two opposite electrodes. For instance,multi-layered devices usually comprise at least three layers: a holeinjection/transport layer, an emissive layer and an electron transportlayer (ETL). Furthermore, it is also preferred that the holeinjection/transport layer serves as an electron blocking layer and theETL as a hole blocking layer. Single-layered OLEDs comprise only onelayer of materials between two opposite electrodes.

BRIEF DESCRIPTION

In one aspect, the invention relates to a process comprising:

reacting a compound of formula A and a compound of formula B to form acompound of formula C; and

reacting one of the compound of formula C and the compound of formula. Dwith a first boron esterification reagent to generate a boronic acid ora boronic ester to react with another of the compound of formula C andthe compound of formula D to form a compound of formula E;

-   -   wherein R¹, R², and R³ are, independently at each occurrence, a        C₁-C₂₀ aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀        cycloaliphatic radical;    -   X1 is chloro, bromo, trifluoromethanesulfonate, or hydroxy;    -   X2 is chloro, bromo, iodo; and when X1 is chloro, X2 is bromo or        iodo, when X1 is bromo, X2 is iodo, when X1 is hydroxy, X2 is        chloro, bromo or iodo, when X1 is trifluoromethanesulfonate, X2        is bromo or iodo;    -   X3 is a boronic acid or boronic ester;    -   X is CH or N and when X is CH, at least one of R² is pyridyl;    -   X4 is chloro, bromo, trifluoromethanesulfonate, or hydroxy;    -   X5 is chloro, bromo, iodo; and when X4 is chloro, X5 is bromo or        iodo, when X4 is bromo, X5 is iodo, when X4 is hydroxy, X5 is        chloro, bromo or iodo, when X4 is trifluoromethanesulfonate, X5        is bromo or iodo;    -   a, and c are, independently at each occurrence, an integer        ranging from 0-4; and    -   b is an integer ranging from 0-3.

In another aspect, the invention relates to a compound of formula IV:

wherein

-   -   R¹, R², and R³ are, independently at each occurrence, a C₁-C₂₀        aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀        cycloaliphatic radical;    -   Ar is heteroaryl, aryl, alkyl or cycloalkyl;    -   b and c are, independently at each occurrence, an integer        ranging from 0-4;    -   a is an integer ranging from 0-3; and    -   n is an integer ranging from 2 to 4.

In yet another aspect, the invention relates to a process, comprising:

reacting a compound of formula F with 1-chloro-3,5-dibromobenzene toform a compound of formula G;

reacting the compound of formula G with pinacol diborane to form acompound of formula H;

reacting the compound of formula H with 1-bromo-3-iodobenzene to form acompound of formula J; and

reacting the compound of formula J with pinacol diborane to form acompound of formula K; and

reacting the compound of formula K with 3,5-dibromopyridine to form acompound of formula II.

DETAILED DESCRIPTION

In one aspect, the invention relates to a process comprising:

reacting a compound of formula A and a compound of formula B to form acompound of formula C; and

reacting one of the compound of formula C and the compound of formula Dwith a first boron esterification reagent to generate a boronic acid ora boronic ester to react with another of the compound of formula C andthe compound of formula D to form a compound of formula E;

-   -   wherein R¹, R², and R³ are, independently at each occurrence, a        C₁-C₂₀ aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀        cycloaliphatic radical;    -   X1 is chloro, bromo, trifluoromethanesulfonate, or hydroxy;    -   X2 is chloro, broino, iodo; and when X1 is chloro, X2 is bromo        or iodo, when X1 is bromo, X2 is iodo, when X1 is hydroxy, X2 is        chloro, bromo or iodo, when X1 is trifluoromethanesulfonate, X2        is bromo or iodo;    -   X3 is a boronic acid or boronic ester:    -   X is CH or N and when X is CH, at least one of R² is pyridyl;    -   X4 is chloro, bromo, trifluoromethanesulfonate, or hydroxy;    -   X5 is chloro, bromo, iodo; and when X4 is chloro, X5 is bromo or        iodo, when X4 is bromo, X5 is iodo, when X4 is hydroxy, X5 is        chloro, bromo or iodo, when X4 is trifluoromethanesulfonate, X5        is bromo or iodo;    -   a, and c are, independently at each occurrence, an integer        ranging from 0-4; and    -   b is an integer ranging from 0-3.

In some embodiments, the process further comprises converting thecompound of formula E into a compound of formula:

wherein Ar is heteroaryl, aryl, alkyl or cycloalkyl, n is an integerranging from 2-4.

In some embodiments, the process further comprises converting thecompound of formula E into a compound of formula:

wherein Ar is heteroaryl, aryl, alkyl or cycloalkyl, n is an integerranging from 2-4.

In some embodiments, the process further comprises converting thecompound of formula E into a compound of formula:

wherein Ar is heteroaryl, aryl, alkyl or cycloalkyl, n is an integerranging from 2-4.

In some embodiments, the process further comprises reacting the compoundof formula E with a second boron esterification reagent to generate aboronic acid or a boronic ester to react with a pyridyl dihalide to forma compound of formula I

-   -   wherein    -   R¹, R², R³, and R⁴ are, independently at each occurrence, a        C₁-C₂₀ aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀        cycloaliphatic radical;    -   X is CH or N and when X is CH, at least one of R² is pyridyl;    -   a, c, and d are, independently at each occurrence, an integer        ranging from 0-4; and    -   b is an integer ranging from 0-3.

In some embodiments, the first and the second boron esterificationreagents are pinacol diborane and the pyridyl dihalide is

In some embodiments, the compound of formula D is of formula

In some embodiments, the compound of formula A is1-chloro-3,5-dibromobenzene and the compound of B is of formula

In some embodiments, the compound of formula C is of formula

In some embodiments, the compound of formula C reacts with pinacoldiborane to generate a compound of formula H to react with the compoundof formula D.

In some embodiments, the process further comprises reacting3-(3-bromophenyl)pyridine with pinacol diborane to form the compound offormula F.

In some embodiments, the compound of formula E is of

In some embodiments, the process further comprises converting thecompound of formula J into a compound of formula K

In some embodiments, the compound of formula I is of formula II

In some embodiments, the compound of formula C is of formula

In some embodiments, the compound of formula A is1-chloro-3,5-dibromobenzene and the compound of formula B is 3-pyridineboronic acid.

In some embodiments, the compound of formula C reacts with pinacoldiborane to generate a compound of formula M to react with the compoundof formula D.

In some embodiments, the compound of formula E is of

In some embodiments, the compound of formula I is of formula III

In some embodiments, the compound of formula A is selected from

In another aspect, the present invention relates to a compound offormula IV:

wherein

-   -   R¹, R², and R³ are, independently at each occurrence, a C₁-C₂₀        aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀        cycloaliphatic radical;    -   Ar is heteroaryl, aryl, alkyl or cycloalkyl;    -   b and c are, independently at each occurrence, an integer        ranging from 0-4;    -   a is an integer ranging from 0-3; and    -   n is an integer ranging from 2 to 4.

In some embodiments, Ar is

and R⁴ is a C₁-C₂₀ aliphatic radical, a C₃-C₂₀ aromatic radical, or aC₃-C₂₀ cycloaliphatic radical and d is an integer ranging from 0-4.

In some embodiments, the compound is of formula III

In another aspect, the present invention relates to a process,comprising:

reacting a compound of formula F with 1-chloro-3,5-dibromobenzene toform a compound of formula G;

reacting the compound of formula G with pinacol diborane to form acompound of formula H;

reacting the compound of formula H with 1-bromo-3-iodobenzene to form acompound of formula J; and

reacting the compound of formula J with pinacol diborane to form acompound of formula K; and

reacting the compound of formula K with 3,5-dibromopyridine to form acompound of formula II.

In some embodiments, the process further comprises: reacting3-(3-bromophenyl)pyridine with pinacol diborane to form the compound offormula F.

In some embodiments, the process further comprises: reacting1-bromo-3-iodobenzene with 3-pyridine boronic acid to form3-(3-bromophenyl)pyridine.

The process described herein significantly increases yields of theintermediates, compounds of formula C and E by choosing selectivereactivity of halides, trifluoromethanesulfonate, or hydroxy and in turnincreases yields of the product, compounds of formula II and III. Theprocess described herein can omit column chromatography for some stepsand has higher yield, lower cost and higher productivity, and is thussuitable for mass production.

The process comprises Suzuki cross-coupling reactions in a suitablesolvent, in the presence of a base and Pd catalyst. The reaction mixtureis heated under an inert atmosphere for a period of time. Suitablesolvents include but are not limited to dioxane, THF, EtOH, toluene andmixtures thereof. Exemplary bases include KOAc, Na₂CO₃, K₂CO₃, Cs₂CO₃,potassium phosphate and hydrates thereof. The bases can be added to thereaction as a solid powder or as an aqueous solution. The most commonlyused catalysts include Pd(PPh₃)₄, Pd₂(dba)₃, or Pd(OAc)₂, Pd(dba)₂ withthe addition of a secondary ligand. Exemplary ligands includedialkylphosphinobiphenyl ligands, such as structures V-IX shown below,in which Cy is cyclohexyl.

Compounds of formula I-IV have properties useful in optoelectronicdevices, e.g., organic light emitting devices (OLEDs), and areparticularly well suited for use as electron transporting materials andhole blocking materials for OLEDs as they have LUMO (Lowest UnoccupiedMolecular Orbital) between 2.0 eV and 3.0 eV, and HOMO (Highest OccupiedMolecular Orbital) typically greater than 5.5 eV, most greater than 6.0eV.

An optoelectronic device, e.g., an OLED, typically includes in thesimplest case, an anode layer and a corresponding cathode layer with anorganic electroluminescent layer disposed between said anode and saidcathode. When a voltage bias is applied across the electrodes, electronsare injected by the cathode into the electroluminescent layer whileelectrons are removed from (or “holes” are “injected” into) theelectroluminescent layer from the anode. Light emission occurs as holescombine with electrons within the electroluminescent layer to formsinglet or triplet excitons, light emission occurring as singlet and/ortriplet excitons decay to their ground states via radiative decay.

Other components which may be present in an OLED in addition to theanode, cathode and light emitting material include a hole injectionlayer, an electron injection layer, and an electron transport layer. Theelectron transport layer need not be in direct contact with the cathode,and frequently the electron transport layer also serves as a holeblocking layer to prevent holes migrating toward the cathode. Additionalcomponents which may be present in an organic light-emitting deviceinclude hole transporting layers, hole transporting emission (emitting)layers and electron transporting emission (emitting) layers.

In one embodiment, the OLEDs comprising the organic compounds of theinvention may be a fluorescent OLED comprising a singlet emitter. Inanother embodiment, the OLEDs comprising the organic compounds of theinvention may be a phosphorescent OLED comprising at least one tripletemitter. In another embodiment, the OLEDs comprising the organiccompounds of the invention comprise at least one singlet emitter and atleast one triplet emitter. The OLEDs comprising the organic compounds ofthe invention may contain one or more, any or a combination of blue,yellow, orange, red phosphorescent dyes, including complexes oftransition metals such as Ir, Os and Pt. In particular,electrophosphorescent and electrofluorescent metal complexes, such asthose supplied by American Dye Source, Inc., Quebec, Canada may be used.Compounds of the formula I to IV may be part of an emissive layer, orhole transporting layer or electron transporting layer, or electroninjection layer of an OLED or any combination thereof.

The organic electroluminescent layer, i.e., the emissive layer, is alayer within an organic light emitting device which when in operationcontains a significant concentration of both electrons and holes andprovides sites for exciton formation and light emission. A holeinjection layer is a layer in contact with the anode which promotes theinjection of holes from the anode into the interior layers of the OLED;and an electron injection layer is a layer in contact with the cathodethat promotes the injection of electrons from the cathode into the OLED;an electron transport layer is a layer which facilitates conduction ofelectrons from the cathode and/or the electron injection layer to acharge recombination site. During operation of an organic light emittingdevice comprising an electron transport layer, the majority of chargecarriers (i.e. holes and electrons) present in the electron transportlayer are electrons and light emission can occur through recombinationof holes and electrons present in the emissive layer. A holetransporting layer is a layer which when the OLED is in operationfacilitates conduction of holes from the anode and/or the hole injectionlayer to charge recombination sites and which need not be in directcontact with the anode. A hole transporting emission layer is a layer inwhich when the OLED is in operation facilitates the conduction of holesto charge recombination sites, and in which the majority of chargecarriers are holes, and in which emission occurs not only throughrecombination with residual electrons, but also through the transfer ofenergy from a charge recombination zone elsewhere in the device. Anelectron transporting emission layer is a layer in which when the OLEDis in operation facilitates the conduction of electrons to chargerecombination sites, and in which the majority of charge carriers areelectrons, and in which emission occurs not only through recombinationwith residual holes, but also through the transfer of energy from acharge recombination zone elsewhere in the device.

Materials suitable for use as the anode includes materials having a bulkresistivity of preferred about 1000 ohms per square, as measured by afour-point probe technique. Indium tin oxide (ITO) is frequently used asthe anode because it is substantially transparent to light transmissionand thus facilitates the escape of light emitted from electro-activeorganic layer. Other materials, which may be utilized as the anodelayer, include tin oxide, indium oxide, zinc oxide, indium zinc oxide,zinc indium tin oxide, antimony oxide, and mixtures thereof.

Materials suitable for use as the cathode include general electricalconductors including, but not limited to metals and metal oxides such asITO etc which can inject negative charge carriers (electrons) into theinner layer(s) of the OLED. Various metals suitable for use as thecathode include K, Li, Na, Cs, Mg, Ca, Sr, Ba, Al, Ag, Au, In, Sn, Zn,Zr, Sc, Y, elements of the lanthanide series, alloys thereof, andmixtures thereof. Suitable alloy materials for use as the cathode layerinclude Ag—Mg, Al—Li, In—Mg, Al—Ca, and Al—Au alloys. Layered non-alloystructures may also be employed in the cathode, such as a thin layer ofa metal such as calcium, or a metal fluoride, such as LiF, covered by athicker layer of a metal, such as ahluminum or silver. In particular,the cathode may be composed of a single metal, and especially ofaluminum metal.

Compounds of formula I to IV may be used in electron transport layers inplace of, or in addition to traditional materials such aspoly(9,9-dioctyl fluorene), tris(8-hydroxyquinolato) aluminum (Alq₃),2,9-dimethyl-4,7-diphenyl-1,1-phenanthroline,4,7-diphenyl-1,10-phenanthroline,2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole,3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole,1,3,4-oxadiazole-containing polymers, 1,3,4-triazole-containingpolymers, quinoxaline-containing polymers, and cyano-PPV.

Materials suitable for use in hole transporting layers include1,1-bis((di-4-tolylamino)phenyl)cyclohexane,N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-(1,1′-(3,3′-dimethyl)biphenyl)-4,4′-diamine,tetrakis-(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine,phenyl-4-N,N-diphenylaminostyrene, p-(diethylamino)benzaldehydediphenylhydrazone, triphenylamine,1-phenyl-3-(p-(diethylamino)styryl)-5-(p-(diethylamino)phenyl)pyrazoline,1,2-trans-bis(9H-carbazol-9-yl)cyclobutane,N,N,N′,N′-tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine, copperphthalocyanine, polyvinylcarbazole, (phenylmethyl)polysilane;poly(3,4-ethylendioxythiophene) (PEDOT), polyaniline,polyvinylcarbazole, triaryldiamine, tetraphenyldiamine, aromatictertiary amines, hydrazone derivatives, carbazole derivatives, triazolederivatives, imidazole derivatives, oxadiazole derivatives having anamino group, and polythiophenes as disclosed in U.S. Pat. No. 6,023,371.

Materials suitable for use in the light emitting layer includeelectroluminescent polymers such as polyfluorenes, preferablypoly(9,9-dioctyl fluorene) and copolymers thereof, such aspoly(9,9′-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)diphenylamine)(F8-TFB); poly(vinylcarbazole) and polyphenylenevinylene and theirderivatives. In addition, the light emitting layer may include a blue,yellow, orange, green or red phosphorescent dye or metal complex, or acombination thereof. Materials suitable for use as the phosphorescentdye include, but are not limited to, tris(1-phenylisoquinoline) iridium(III) (red dye), tris(2-phenylpyridine) iridium (green dye) and iridium(III) bis(2-(4,6-difluorephenyl)pyridinato-N,C2) (blue dye).Commercially available electrofluorescent and electrophosphorescentmetal complexes from ADS (American Dyes Source, Inc.) may also be used.ADS green dyes include ADS060GE, ADS061GE, ADS063GE, and ADS066GE,ADS078GE, and ADS090GE. ADS blue dyes include ADS064BE, ADS065BE, andADS070BE. ADS red dyes include ADS067RE, ADS068RE, ADS069RE, ADS075RE,ADS076RE, ADS067RE, and ADS077RE.

Organic compounds of formula I to IV may form part of the electrontransport layer or electron injection layer or light emissive layer ofoptoelectronic devices, e.g., OLEDs. The OLEDs may be phosphorescentcontaining one or more, any or a combination of, blue, yellow, orange,green, red phosphorescent dyes.

DEFINITIONS

As used herein, the term “aromatic radical” refers to an array of atomshaving a valence of at least one comprising at least one aromatic group.The array of atoms having a valence of at least one comprising at leastone aromatic group may include heteroatoms such as nitrogen, sulfur,selenium, silicon and oxygen, or may be composed exclusively of carbonand hydrogen. As used herein, the term “aromatic radical” includes butis not limited to phenyl, pyridyl, furanyl, thienyl, naphthyl,phenylene, and biphenyl radicals. As noted, the aromatic radicalcontains at least one aromatic group. The aromatic group is invariably acyclic structure having 4n+2 “delocalized” electrons where “n” is aninteger equal to 1 or greater, as illustrated by phenyl groups (n=1),thienyl groups (n=1), furanyl groups (n=1), naphthyl groups (n=2),azulenyl groups (n=2), and anthraceneyl groups (n=3). The aromaticradical may also include nonaromatic components. For example, a benzylgroup is an aromatic radical which comprises a phenyl ring (the aromaticgroup) and a methylene group (the nonaromatic component). Similarly atetrahydronaphthyl radical is an aromatic radical comprising an aromaticgroup (C₆H₃) fused to a nonaromatic component —(CH₂)₄—. For convenience,the term “aromatic radical” is defined herein to encompass a wide rangeof functional groups such as alkyl groups, alkenyl groups, alkynylgroups, haloalkyl groups, haloaromatic groups, conjugated dienyl groups,alcohol groups, ether groups, aldehydes groups, ketone groups,carboxylic acid groups, acyl groups (for example carboxylic acidderivatives such as esters and amides), amine groups, nitro groups, andthe like. For example, the 4-methylphenyl radical is a C₇ aromaticradical comprising a methyl group, the methyl group being a functionalgroup which is an alkyl group. Similarly, the 2-nitrophenyl group is aC₆ aromatic radical comprising a nitro group, the nitro group being afunctional group. Aromatic radicals include halogenated aromaticradicals such as 4-trifluoromethylphenyl,hexafluoroisopropylidenebis(4-phen-1-yloxy) (i.e., —OPhC(CF₃)₂PhO—),4-chloromethylphen-1-yl, 3-trifluorovinyl-2-thienyl,3-trichloromethylphen-1-yl (i.e., 3-CCl₃Ph-),4-(3-bromoprop-1-yl)phen-1-yl (i.e., 4-BrCH₂CH₂CH₂Ph-), and the like.Further examples of aromatic radicals include 4-allyloxyphen-1-oxy,4-aminophen-1-yl (i.e., 4-H₂NPh-), 3-aminocarbonylphen-1-yl (i.e.,NH₂COPh-), 4-benzoylphen-1-yl, dicyanomethylidenebis(4-phen-1-yloxy)(i.e., —OPhC(CN)₂PhO—), 3-methylphen-1-yl, methylenebis(4-phen-1-yloxy)(i.e., —OPhCH₂PhO—), 2-ethylphen-1-yl, phenylethenyl,3-formyl-2-thienyl, 2-hexyl-5-furanyl,hexamethylene-1,6-bis(4-phen-1-yloxy) (i.e., —OPh(CH₂)₆PhO—),4-hydroxymethylphen-1-yl (i.e., 4-HOCH₂Ph-), 4-mercaptomethylphen-1-yl(i.e., 4-HSCH₂Ph-), 4-methylthiophen-1-yl (i.e., 4-CH₃SPh-),3-methoxyphen-1-y, 2-methoxycarbonylphen-1-yloxy (e.g. methyl salicyl),2-nitromethylphen-1-yl (i.e., 2-NO₂CH₂Ph), 3-trimethylsilylphen-1-yl,4-t-butyldimethylsilylpheni-1-yl, 4-vinylphen-1-yl,vinylidenebis(phenyl), and the like. The term “a C₃-C₁₀ aromaticradical” includes aromatic radicals containing at least three but nomore than 10 carbon atoms. The aromatic radical 1-imidazolyl (C₃H₂N₂—)represents a C₃ aromatic radical. The benzyl radical (C₇H₇—) representsa C₇ aromatic radical.

As used herein the term “cycloaliphatic radical” refers to a radicalhaving a valence of at least one, and comprising an array of atoms whichis cyclic but which is not aromatic. As defined herein a “cycloaliphaticradical” does not contain an aromatic group. A “cycloaliphatic radical”may comprise one or more noncyclic components. For example, acyclohexylmethyl group (C₆H₁₁CH₂—) is an cycloaliphatic radical whichcomprises a cyclohexyl ring (the array of atoms which is cyclic butwhich is not aromatic) and a methylene group (the noncyclic component).The cycloaliphatic radical may include heteroatoms such as nitrogen,sulfur, selenium, silicon and oxygen, or may be composed exclusively ofcarbon and hydrogen. For convenience, the term “cycloaliphatic radical”is defined herein to encompass a wide range of functional groups such asalkyl groups, alkenyl groups, alkynyl groups, haloalkyl groups,conjugated dienyl groups, alcohol groups, ether groups, aldehyde groups,ketone groups, carboxylic acid groups, acyl groups (for examplecarboxylic acid derivatives such as esters and amides), amine groups,nitro groups, and the like. For example, the 4-methylcyclopent-1-ylradical is a C₆ cycloaliphatic radical comprising a methyl group, themethyl group being a functional group which is an alkyl group.Similarly, the 2-nitrocyclobut-1-yl radical is a C₄ cycloaliphaticradical comprising a nitro group, the nitro group being a functionalgroup. A cycloaliphatic radical may comprise one or more halogen atomswhich may be the same or different. Halogen atoms include, for example;fluorine, chlorine, bromine, and iodine. Cycloaliphatic radicalscomprising one or more halogen atoms include2-trifluoromethylcyclohex-1-yl, 4-bromodifluoromethylcyclooct-1-yl,2-chlorodifluoromethylcyclohex-1-yl,hexafluoroisopropylidene-2,2-bis(cyclohex-4-yl) (i.e.,—-C₆H₁₀(CF₃)₂C₆H₁₀—), 2-chloromethyleyclohex-1-yl,3-difluoronmethylenecyclohex-1-yl, 4-trichloromethylcyclohex-1-yloxy,4-bromodichloromethyleyclohex-1-ylthio, 2-bromoethylicyclopent-1-yl,2-bromopropylcyclohex-1-yloxy (e.g. CH₃CHBrCH₂C₆H₁₀O—), and the like.Further examples of cycloaliphatic radicals include4-allyloxycyclohex-1-yl, 4-aminocyclohex-1-yl (i.e., H₂C₆H₁₀O—),4-aminocarbonylcyclopent-1-yl (i.e., NH₂COC₅H₈—),4-acetyloxycyclohex-1-yl, 2,2-dicyanoisopropylidenebis(cyclohex-4-yloxy)(i.e., —OC₆H₁₀C(CN)₂CH₁₀O—), 3-methylcyclohex-1-yl,methylenebis(cyclohex-4-yloxy) (i.e., —OC₆H₁₀CH₂C₆H₁₀O—),1-ethylcyclobut-1-yl, cyclopropylethenyl, 3-formyl-2-tetrahydrofuranyl,2-hexyl-5-tetrahydrofuranyl, hexamethylene-1,6-bis(cyclohex-4-yloxy)(i.e., —OC₆H₁₀(CH₂)₆C₆H₁₀O—), 4-hydroxymethylcyclohex-1-yl (i.e.,4-HOCH₂C₆H₁₀—), 4-mercaptomethylcyclohex-1-yl (i.e., 4-HSCH₂C₆H₁₀—),4-methylthiocyclohex-1-yl (i.e., 4-CH₃SC₆H₁₀—), 4-methoxycyclohex-1-yl,2-methoxycarbonyleyclohex-1-yloxy (2-CH₃OCOC₆H₁₀O—),4-nitromethylcyclohex-1-yl (i.e., NO₂CH₂C₆H₁₀—),3-trimethylsilylcyclohex-1-yl, 2-t-butyldimethylsilylcyclopent-1-yl,4-trimethoxysilylethylcyclohex-1-yl (e.g. (CH₃O)₃SiCH₂CH₂C₆H₁₀—),4-vinylcyclohexen-1-yl, vinylidenebis(cyclohexyl), and the like. Theterm “a C₃-C₁₀ cycloaliphatic radical” includes cycloaliphatic radicalscontaining at least three but no more than 10 carbon atoms. Thecycloaliphatic radical 2-tetrahydrofuranyl (C₄H₇O—) represents a C₄cycloaliphatic radical. The cyclohexylmethyl radical (C₆H₁₁CH₂—)represents a C₇ cycloaliphatic radical.

As used herein the term “aliphatic radical” refers to an organic radicalhaving a valence of at least one consisting of a linear or branchedarray of atoms which is not cyclic. Aliphatic radicals are defined tocomprise at least one carbon atom. The array of atoms comprising thealiphatic radical may include heteroatoms such as nitrogen, sulfur,silicon, selenium and oxygen or may be composed exclusively of carbonand hydrogen. For convenience, the term “aliphatic radical” is definedherein to encompass, as part of the “linear or branched array of atomswhich is not cyclic” organic radicals substituted with a wide range offunctional groups such as alkyl groups, alkenyl groups, alkynyl groups,haloalkyl groups, conjugated dienyl groups, alcohol groups, ethergroups, aldehyde groups, ketone groups, carboxylic acid groups, acylgroups (for example carboxylic acid derivatives such as esters andamides), amine groups, nitro groups, and the like. For example, the4-methylpent-1-yl radical is a C₆ aliphatic radical comprising a methylgroup, the methyl group being a functional group which is an alkylgroup. Similarly, the 4-nitrobut-1-yl group is a C₄ aliphatic radicalcomprising a nitro group, the nitro group being a functional group. Analiphatic radical may be a haloalkyl group which comprises one or morehalogen atoms which may be the same or different. Halogen atoms include,for example; fluorine, chlorine, bromine, and iodine. Aliphatic radicalscomprising one or more halogen atoms include the alkyl halidestrifluoromethyl, bromodifluoromethyl, chlorodifluoromethyl,hexafluoroisopropylidene, chloromethyl, difluorovinylidene,trichloromethyl, bromodichloromethyl, bromoethyl, 2-bromotrimethylene(e.g. CH₂CHBrCH₂—), and the like. Further examples of aliphatic radicalsinclude allyl, aminocarbonyl (i.e., —CONH₂), carbonyl,2,2-dicyanoisopropylidene (i.e., CH₂C(CN)₂CH₂—), methyl (i.e., —CH₃),methylene (i.e., —CH₂—), ethyl, ethylene, formyl (i.e. —CHO), hexyl,hexamethylene, hydroxymethyl (i.e. —CH₂OH), mercaptomethyl (i.e.,—CH₂SH), methylthio (i.e., —SH₃), methylthiomethyl (i.e., —CH₂SCH₃),methoxy, methoxycarbonyl (i.e., CH₃OCO—), nitromethyl (i.e., —CH₂NO₂),thiocarbonyl, trimethylsilyl (i.e., (CH₃)₃Si—), t-butyldimethylsilyl,3-trimethyoxysilypropyl (i.e., (CH₃O)₃SiCH₂CH₂CH₂—), vinyl, vinylidene,and the like. By way of further example, a C₁-C₁₀ aliphatic radicalcontains at least one but no more than 10 carbon atoms. A methyl group(i.e., CH₃—) is an example of a C₁ aliphatic radical. A decyl group(i.e., CH₃ (CH₂)₉—) is an example of a C₁₀ aliphatic radical.

The term “heteroaryl” as used herein refers to aromatic or unsaturatedrings in which one or more carbon atoms of the aromatic ring(s) arereplaced by a heteroatom(s) such as nitrogen, oxygen, boron, selenium,phosphorus, silicon or sulfur. Heteroaryl refers to structures that maybe a single aromatic ring, multiple aromatic ring(s), or one or morearomatic rings coupled to one or more non-aromatic ring(s). Instructures having multiple rings, the rings can be fused together,linked covalently, or linked to a common group such as an ether,methylene or ethylene moiety. The common linking group may also be acarbonyl as in phenyl pyridyl ketone. Examples of heteroaryl ringsinclude thiophene, pyridine, isoxazole, pyrazole, pyrrole, furan,imidazole, indole, thiazole, benzimidazole, quinoline, isoquinoline,quinoxaiine, pyrimidine, pyrazine, tetrazole, triazole, benzo-fusedanalogues of these groups, benzopyranone, phenylpyridine, tolylpyridine,benzothienylpyridine, phenylisoquinoline, dibenzoquinozaline,fluorenylpyridine, ketopyrrole, 2-phenylbenzoxazole, 2phenylbenzothiazole, thienylpyridine, benzothienylpyridine, 3methoxy-2-phenylpyridine, phenylimine, pyridylnaphthalene,pyridylpyrrole, pyridylimidazole, and phenylindole.

The term “aryl” is used herein to refer to an aromatic substituent whichmay be a single aromatic ring or multiple aromatic rings which are fusedtogether, linked covalently, or linked to a common group such as anether, methylene or ethylene moiety. The aromatic ring(s) may includephenyl, naphthyl, anthracenyl, and biphenyl, among others. In particularembodiments, aryls have between 1 and 200 carbon atoms, between 1 and 50carbon atoms or between 1 and 20 carbon atoms.

The term “alkyl” is used herein to refer to a branched or unbranched,saturated or unsaturated acyclic hydrocarbon radical. Suitable alkylradicals include, for example, methyl, ethyl, n-propyl, i-propyl,2-propenyl (or allyl), vinyl, n-butyl, t-butyl, i-butyl (or2-methylpropyl), etc. In particular embodiments, alkyls have between 1and 200 carbon atoms, between 1 and 50 carbon atoms or between 1 and 20carbon atoms.

The term “cycloalkyl” is used herein to refer to a saturated orunsaturated cyclic non-aromatic hydrocarbon radical having a single ringor multiple condensed rings. Suitable cycloalkyl radicals include, forexample, cyclopentyl, cyclohexyl, cyclooctenyl, bicyclooctyl, etc. Inparticular embodiments, cycloalkyls have between 3 and 200 carbon atoms,between 3 and 50 carbon atoms or between 3 and 20 carbon atoms.

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent or a value of a process variable such as, for example,temperature, pressure, time and the like is, for example, from 1 to 90,preferably from 20 to 80, more preferably from 30 to 70, it is intendedthat values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. areexpressly enumerated in this specification. For values which are lessthan one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 asappropriate. These are only examples of what is specifically intendedand all possible combinations of numerical values between the lowestvalue and the highest value enumerated are to be considered to beexpressly stated in this application in a similar manner.

EXAMPLES

Examples 1-12 describe the syntheses of compounds of formula II-III, andintermediates used in making them. All reagents were purchased fromAldrich Chemical Co., Milwaukee, Wis., USA unless otherwise specifiedand were used without further purification. All compounds werecharacterized by ¹H-NMR and found to correspond to the structures shown.

Example 1 Synthesis of 3-(3-bromophenyl)pyridine

1-bromo-3-iodobenzene (1.118 g, 3.95 mol) and 3-pyridine boronic acid(0.559 g, 4.54 mol) were added to a 100 mL three neck round bottomflask. To this flask, dioxane (20 mL) and aqueous K₂CO₃ (2 N, 20 mL)were added. The mixture was stirred and degassed with a steam of argonfor 30 minutes. Then under argon atmosphere, 50 mg (0.04 mmol) ofPd(PPh₃)₄ (1%) was added. The mixture was heated to 100° C. and stirredovernight. The next day, the solvent was removed by roto-evaporation andthe residue was suspended into an equal amount of water (50 mL) andCH₂Cl₂ (50 mL). The organic layer was separated from aqueous layer andwashed with brine (50 mL×3). After drying over Na₂SO₄, and removal ofthe drying agent, about 0.92 g of 3-(3-bromophenyl)pyridine product(100%) was afforded. ¹H NMR (400 MHz, CDC₃) 8.85 (s, 1H), 8.65 (d, 1H),7.87 (d, 1H), 7.75 (s, 1H), 7.57-7.52 (m, 2H), 7.41-7.35 (m, 2H).

Example 2 Synthesis of Compound of Formula F

To a schlenk tube was charged 3-(3-bromophenyl)pyridine (4.18 g, 17.8mmol), pinacol diborane (4.63 g, 18.2 mmol), dry KOAc (3.5 g, 35.7mmol), ligand PCyBin (600 mg, 1.46 mmol, 8%) and Pd₂(dba)₃ (300 mg, 0.33mmol, 2%). The Schlenk tube was evacuated and filled with argon threetimes. The Schlenk tube was placed in an argon atmosphere. Anhydrousdioxane (70 mL) was added. The Schlenk tube was then heated at 110° C.for 3 hours under argon atmosphere. An aliquot was removed (0.5 mL),filtered, washed with EtOAc, concentrated to dryness. This aliquot wasanalyzed by ¹H NMR spectroscopy and revealed that all of the monobromidewas converted into the corresponding boron ester. ¹H NMR (400 MHz,CDCl₃) 8.90 (s, 1H), 8.60 (d, 1H), 8.05 (d, 1H), 7.95 (d, 1H), 7.87 (d,1H), 7.70 (d, 1H), 7.53-7.49 (m, 1H), 7.40-7.37 (m, 1H), 1.38 (s, 12H).

Example 3 Synthesis of Compound of Formula G

Potassium phosphate mono-hydrate (K₃PO₄.H₂O, 8 g, 40 mmol, 2 equiv) and1-chloro-3,5-dibromobenzene (2.4 g, 8.93 mmol) were added into thereaction solution of EXAMPLE 2, then refluxed at 110° C. overnight underargon atmosphere. Then cooled to ambient temperature. Distilled water(30 mL) was added via a funnel, and the resulting mixture was filteredon a Büchner funnel. The filtrate was transferred to a separatory funneland extracted with CH₂Cl₂ (3×50 mL). The combined organic phases weredried over Na₂SO₄, filtered on filter paper and concentrated to drynessby rotary evaporation (30° C., 25 mmHg). The resulting yellow solid waspurified by column chromatography to afford 3.33 g white solid (90%).Compound G: ¹H NMR (400 MHz, CDCl₃), 8.97 (s, 2H), 8.67 (d, 2H), 8.08(d, 2H), 7.84 (s, 2H), 7.76 (s, 1H), 7.73-7.71 (m, 2H), 7.66-7.63 (m,6H), 7.54-7.50 (m, 2H).

Example 4 Synthesis of Compound H

To a schlenk tube was charged compound G (1.57 g, 3.8 mmol), pinacoldiborane (1.00 g, 3.9 mmol), dry KOAc (0.74 g, 7.6 mmol), ligand PCyBin(140 mg, 0.34 mmol, 8%) and Pd₂(dba)₃ (70 mg, 0.076 mmol, 2%). TheSchlenk tube was evacuated and filled with argon three times. TheSchlenk tube was placed in an argon atmosphere. Anhydrous dioxane (15mL) was added. The Schlenk tube was then heated at 110° C. for 5 hoursunder argon atmosphere. An aliquot was removed (0.5 mL), filtered,washed with EtOAc, concentrated to dryness. This aliquot was analyzed by¹H NMR spectroscopy and revealed that all of the monobromide wasconverted into the corresponding boron ester. ¹H NMR (400 MHz, CDCl₃)8.98 (b, 2H), 8.67 (b, 2H), 8.12-8.08 (m, 4H), 7.99 (s, 1H), 7.89 (s,2H), 7.80-7.76 (m, 2H), 7.62-7.60 (m, 4H), 7.55-7.51 (m, 2H), 1.41 (s,12-1).

Example 5 Synthesis of Compound of Formula J

Compound H (0.71 g, 1.4 mmol), potassium carbonate (K₂CO₃, 2 N, 20 ml),Pd(PPh₃)₄ (50 g, 0.04 mol) and 1-bromo-3-iodobenzene (0.53 g, 1.87 mmol)were dissolved in 1,4-dioxane (20 ml), then refluxed at 110° C.overnight under argon atmosphere. Then cooled to ambient temperature.Distilled water (30 mL) was added via a funnel, and the resultingmixture was filtered on a Büchner funnel. The filtrate was transferredto a separatory funnel and extracted with CH₂Cl₂ (3×30 mL). The combinedorganic phases were dried over Na₂SO₄, filtered on filter paper andconcentrated to dryness by rotary evaporation (30° C., 25 mmHg). The oilproduct was washed with hexane (2×20 mL), and precipitated in ethanol(20 mL) to yield yellow powder (˜0.73 g, 97%) compound of formula J: ¹HNMR (400 MHz, CDCl₃), 8.95 (s, 2H), 8.65 (d, 2H), 7.98 (d, 2H),7.91-7.88 (m, 4H), 7.84 (s, 2H), 7.78-7.75 (m, 2H), 7.68-7.64 (m, 5H),7.56 (d, 1H), 7.44-7.38 (m, 3H).

Example 6 Synthesis of Compound of Formula K

To a schlenk tube was charged1,3-bis(3-pyridinephenyl)-5-(3-bromophenyl)benzene (compound J, 5.7 g,10.55 mmol), pinacol diborane (2.82 g, 11.10 mmol), dry KOAc (2.2 g,21.1 mmol), ligand PCyBin (400 mg, 0.97 mmol, 8%) and Pd₂(dba)₃ (200 mg,0.218 mmol, 2%). The schlenk tube was evacuated and filled with argonthree times. The schlenk tube was placed in an argon atmosphere.Anhydrous dioxane (40 mL) was added. The Schlenk tube was then heated at110° C. for 5 hours under argon atmosphere. An aliquot was removed (0.5mL), filtered, washed with EtOAc, concentrated to dryness. This aliquotwas analyzed by ¹H NMR spectroscopy and revealed that all of themonobromide was converted into the corresponding boron ester. ¹H NMR(400 MHz, CDCl₃) 8.95 (s, 2H), 8.65 (d, 2H), 8.15 (s, 1H), 7.99 (d,2-H), 7.90-7.82 (m, 7H), 7.78-7.74 (m, 2H), 7.64-7.61 (m, 4H), 7.55-7.50(m, 1H), 7.44-7.40 (m, 2H), 1.38 (s, 12H).

Example 7 Synthesis of Compound of Formula II

Potassium phosphate mono-hydrate (K₃PO₄.H₂O, 5 g, 25 mmol),3,5-dibromopyridine (1080 mg, 4.58 mmol) and 5 ml DI water were addedinto the reaction solution of EXAMPLE 6, then refluxed at 110° C.overnight under argon atmosphere. Then cooled to ambient temperature.Distilled water (50 mL) was added via a funnel, and the resultingmixture was filtered on a Büchner funnel. The filtrate was transferredto a separatory funnel and extracted with CH₂Cl₂ (3×50 mL). The combinedorganic phases were dried over Na₂SO₄, filtered on filter paper andconcentrated to dryness by rotary evaporation (30° C., 25 mmHg). Theresulting yellow solid was purified by column chromatography to afford4.0 g white solids (88%). ¹H NMR (400 MHz, CDCl₃) δ 8.94 (m, 6H), 8.64(m, 4H), 8.20 (m, 1H), 7.97-7.91 (m, 16H), 7.82-7.63 (m, 18H), 7.41 (m,4H).

Example 8 Synthesis of Compound of Formula L

1-chloro-3,5-dibromobenzene (5.40 g, 20 mmol) and 3-pyridine boronicacid (5.17 g, 42 mmol) were added to a 100 mL three neck round bottomflask. To this flask, dioxane (80 mL) and aqueous K₂CO₃ (2 N, 40 mL)were added. The mixture was stirred and degassed with a stream of argonfor 30 minutes. Then under argon atmosphere, 200 mg (0.16 mmol)Pd(PPh₃)₄ was added. The mixture was brought to 100° C. and stirredovernight. The next day, solvent was removed by roto-evaporation andresidue was suspended into an equal amount of water (50 mL) and CH₂Cl₂(50 mL). The organic layer was separated from aqueous layer and washedwith brine (50 mL×3). After drying over Na₂SO₄, and removal of dryingagent, ˜5.33 g transparent liquid3,3′-(5-chloro-1,3-phenylene)dipyridine (100%, Compound L) was obtained.¹H NMR (400 MHz, CDCl₃) 8.91 (s, 2H), 8.69 (d, 2H), 7.95 (d, 2H), 7.66(s, 1H), 7.63 (s, 2H), 7.50-7.44 (m, 2H).

Example 9 Synthesis of Compound of Formula M

To a schlenk tube was charged compound L (5.35 g, 20 mmol), pinacoldiborane (5.08 g, 20 mmol, 1.0 eq), dry KOAc (4.0 g, 40.8 mmol, 2 eq),ligand PCyBin (720 mg, 1.75 mmol, 8%) and Pd₂(dba)₃ (360 mg, 0.40 mmol,2%). The Schlenk tube was evacuated and filled with argon three times.The Schlenk tube was placed in an argon atmosphere. Anhydrous dioxane(80 mL) was added. The Schlenk tube was then heated at 115° C. for 3hours under argon atmosphere. An aliquot was removed (0.5 mL), filtered,washed with EtOAc, concentrated to dryness. This aliquot was analyzed by¹H NMR spectroscopy and revealed that all of the monobromide wasconverted into the corresponding boron ester. ¹H NMR (400 MHz, CDCl₃)8.94 (s, 2H), 8.64 (d, 2H), 8.08 (s, 2H), 8.00 (d, 2H), 7.86 (s, 1H),7.45-7.39 (m, 2H), 1.39 (s, 12H).

Example 10 Synthesis of Compound of Formula N

Compound M (3.58 g, 10 mmol) and 1-bromo-3-iodobenzene (3.68 g, 13 mmol)were added to a 100 mL three neck round bottom flask. To this flask,dioxane (40 mL) and aqueous K₂CO₃ (2 N, 40 mL) were added. The mixturewas stirred and degassed with a stream of argon for 30 minutes. Thenunder argon atmosphere, 100 mg (0.08 mmol) Pd(PPh₃)₄ was added. Themixture was brought to 100° C. and stirred overnight. The next day, thesolvent was removed by roto-evaporation and the residue was suspendedinto an equal amount of water (50 mL) and CH₂Cl₂ (50 mL). The organiclayer was separated from the aqueous layer and washed with brine (50mL×3). After drying over Na₂SO₄, and removal of drying agent, the oilproduct was washed with hexane (20 mL 3), and precipitated in methanol(20 mL) to yield white powder compound N (3.87 g, ˜100%): ¹H NMR (400MHz, CDCl₃) 8.99 (s, 2H), 8.70 (s, 2H), 8.09 (d, 2H), 7.85 (s, 1H), 7.80(d, 3H), 7.65-7.45 (m, 4H), 7.42-7.35 (m, 1H).

Example 11 Synthesis of Compound of Formula O

To a schlenk tube was charged 3,3′-(3′-bromobiphenyl-3,5-diyl)dipyridine(compound N, 2.0 g, 5.15 mmol), pinacol diborane (1.31 g, 5.15 mmol, 1.0eq), dry KOAc (1.0 g, 10 mmol, 2 eq), ligand PCyBin (180 mg, 0.44 mmol,8%) and Pd₂(dba)₃ (90 mg, 0.1 mmol, 2%). The schlenk tube was evacuatedand filled with argon three times. The schlenk tube was placed in anargon atmosphere. Anhydrous dioxane (20 mL) was added. The Schlendk tubewas then heated at 110° C. for 5 hours under argon atmosphere. Analiquot was removed (0.5 mL), filtered, washed with EtOAc, concentratedto dryness. This aliquot was analyzed by ¹H NMR spectroscopy andrevealed that all of the monobromide was converted into thecorresponding boron ester. ¹H NMR (400 MHz, CDCl₃) 8.95 (s, 2H), 8.65(d, 2H), 8.11 (s, 1H), 8.03 (d, 2H), 7.88-7.85 (m, 3H), 7.78 (d, 1H),7.73 (s, 1H), 7.53-7.43 (m, 3H), 1.37 (s, 12H).

Example 12 Synthesis of Compound of Formula III

Potassium phosphate mono-hydrate (K₃PO₄.H₂O, 2.3 g, 10 mmol) and3,5-dibromopyridine (567 mg, 2.4 mmol) were added into the reactionsolution of EXAMPLE 11, then refluxed at 110° C. overnight under argonatmosphere. Then cooled to ambient temperature. Distilled water (50 mL)was added via a funnel, and the resulting mixture was filtered on aBüchner funnel. The filtrate was transferred to a separatory funnel andextracted with CH₂Cl₂ (3×30 mL). The combined organic phases were driedover Na₂SO₄, filtered on filter paper and concentrated to dryness byrotary evaporation (30° C., 25 mmHg). The resulting yellow solid waspurified by column chromatography to afford 1.41 g (85%) white solid. ¹HNMR (400 MHz, CDCl₃) 8.98 (s, 4H), 8.95 (s, 2H), 8.68 (d, 4H), 8.19 (s,1H), 8.01 (d, 4H), 7.94 (s, 2H), 7.88 (s, 4H), 7.80-7.65 (m, 8H),7.47-7.42 (m, 4H).

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A compound of formula IV:

wherein R¹, R², and R³ are, independently at each occurrence, a C₁-C₂₀ aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀ cycloaliphatic radical; Ar is heteroaryl, aryl, alkyl or cycloalkyl; b and c are, independently at each occurrence, an integer ranging from 0-4; a is an integer ranging from 0-3; and n is an integer ranging from 2 to
 4. 2. The compound of claim 1, wherein Ar is

and wherein R⁴ is a C₁-C₂₀ aliphatic radical, a C₃-C₂₀ aromatic radical, or a C₃-C₂₀ cycloaliphatic radical and d is an integer ranging from 0-4.
 3. The compound of claim 2, wherein d is
 0. 4. The compound of claim 2, being of formula III


5. The compound of claim 1, wherein a is
 0. 6. The compound of claim 1, wherein b is
 0. 7. The compound of claim 1, wherein c is
 0. 8. The compound of claim 1, wherein n is
 2. 9. A process, comprising: reacting a compound of formula F with 1-chloro-3,5-dibromobenzene to form a compound of formula G;

reacting the compound of formula G with pinacol diborane to form a compound of formula H;

reacting the compound of formula H with 1-bromo-3-iodobenzene to form a compound of formula J; and

reacting the compound of formula J with pinacol diborane to form a compound of formula K; and

reacting the compound of formula K with 3,5-dibromopyridine to form a compound of formula II.


10. The process of claim 9, further comprising: reacting 3-(3-bromophenyl)pyridine with pinacol diborane to form the compound of formula F.
 11. A compound of formula II prepared by: reacting a compound of formula F with 1-chloro-3,5-dibromobenzene to form a compound of formula G;

reacting the compound of formula G with pinacol diborane to form a compound of formula H;

reacting the compound of formula H with 1-bromo-3-iodobenzene to form a compound of formula J; and

reacting the compound of formula J with pinacol diborane to form a compound of formula K; and

reacting the compound of formula K with 3,5-dibromopyridine to form the compound of formula II.


12. The compound of claim 11, wherein the compound of formula F is formed by reacting 3-(3-bromophenyl)pyridine with pinacol diborane. 